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February 2012

Arizona Birth Defect Monitoring Program

150 N 18th Avenue Suite 550

AZ, 85007

ABDMP Data Collection

Definition and Types

Down syndrome is a genetic disease resulting from

chromosomal abnormality in which an individual has all

or part of an extra copy of chromosome 21 1. There are

three types of Down syndrome caused by three types of

abnormal cell division mechanisms involving chromo-

some 21: Trisomy 21, Mosaicism and Robersonian

Translocation.

Trisomy 21- accounts for 90% cases of Down syn-

drome and occurs when an extra full copy of chro-

mosome 21 presents in every cells.

Mosaicism - accounts for less 2% of Down syn-

drome cases and the extra copy of chromosome 21

presents in some, but not all, cells of the individual.

Robersonian Translocation - accounts for about 3-

4% cases of Down syndrome and is due to translo-

cation of chromosome 21 to another chromosome

(usually the chromosome 14) before or at concep-

tion. Thus, individuals with Robersonian transloca-

tion have the usual two copies of chromosome 21,

they also have additional material from chromosome

21. stuck to the translocated chromosome 2.

Facts about Down syndrome 1995-2007*

The ABDMP staff review hospital discharge records, birth,

and death certificates in order to identify potential cases with

Down syndrome. An abstraction list serves to identify each

Down syndrome case. After potential cases are identified, the

medical records are reviewed to confirm that the child is one

year old or younger and has Down syndrome. Once the case

report is completed, it will be entered into the Arizona Birth

Defects Registry 4.

Down Syndrome in Arizona The average incident rate of Down syndrome in Arizona is

between 1995 and 2007* was 12.87 (95% CI: 8.96-16.77) per

10,000 live births for all race/ethnicity. The rates remained

relatively constant over time with a slight decline from 1998

to 2000 (Fig. 1). The exact cause of decline of the incident

rate of Down syndrome is not known. It is likely that folic

acid fortification might have had an impact.

The incident rate of Down syndrome from 1995 to 2007*

fluctuated immensely among the Native American population

(Fig.2) as well as the African-American population (Fig.3).

The average incident rate of Down syndrome for Native

American is 14.32 (95% CI: -1.83-30.47) and 13.33 (95% CI:

-2.13-28.79) for African-American. The incident rate of

Down syndrome for the White (non-Hispanic) population and

the Hispanic population are relatively constant with average

rates of 11.9 (95% CI: 8.41-15.38) (Fig. 4) and 13.67 (95%

CI: 8.24-19.1) (Fig.5), respectively. Statistically, there is no

significant difference between the incident rates among all

race/ethnicity groups (Fig.6).

Some common physical features of Down syndrome

include a flat face with an upward slant to the eye, a

short neck, small ears, and a large tongue; tiny white

spots on the iris of the eye; small hands and feet; a single

crease across the palm of the hand; small pinky fingers

that sometimes curve toward the thumb; poor muscle

tone or loose ligaments 3.

Babies and adults with Down syndrome can have IQ

range from mild to moderate intellectual disability. They

might also have physical problems such as congenital

heart diseases, stomach problems, celiac disease,

dementia, hearing problems, skeleton problems, eye

problems, and thyroid problems 1.

ABDMP Data Collection

CDC estimates that about 6,000 babies in the United States

are born with Down syndrome each year. The frequency in

the United States is about 1 case in 691 live births 5. The risk

of having a child with Down syndrome increases with mater-

nal age, especially among mothers older than 35 years of age.

Also the death rate for the infants with Down syndrome

among the African-American population seems to be higher

than death rates among the White (non-Hispanic) population.

* 2000 and 2001 data were omitted due to incompleteness

United States Estimates

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Down Syndrome in Arizona

Facts about Down syndrome 1995-2007*

Figure 1 illustrates The incident rate of Down syndrome for all races/ethnicity

in Arizona between 1995 and 2007*.

Figure 2: The average incident rate of Down syndrome in the Native American

population between 1995 and 2007* is 14.32 cases per 10,000 live births.

An illustration of the genetic basis of Down syndrome (trisomy 21)

* 2000 and 2001 data were omitted due to incompleteness

Down syndrome associates with mal-formations of organs and systems in 45% of patients 13.

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Down Syndrome in Arizona

Figure 4: The average incident rate of Down syndrome in the White (non-Hispanic)

population between 1995 and 2007* is 11.9 cases per 10,000 live births.

Figure 3: The average incident rate of Down syndrome in the African-American

population between 1995 and 2007* is 13.33 cases per 10,000 live births.

Infants exhibiting the symptoms of

Down syndrome such as flattered

nose and face, upward slanting

eyes, open mouth with tendency of

tongue protrusion, small ear with

overfolded helix, single palmer

crease, short fifth finger that curves

inward, and widely separated first

and second toes and increased skin

crease 3.

Facts about Down syndrome 1995-2007*

* 2000 and 2001 data were omitted due to incompleteness

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Down Syndrome in Arizona

Figure 6: The incident rate of Down syndrome for selected race/ethnicity between

1995 and 2007*.

Figure 5: The average incident rate of Down syndrome in the Hispanic population

between 1995 and 2007* is 13.67 cases per 10,000 live births.

Facts about Down syndrome 1995-2007*

* 2000 and 2001 data were omitted due to incompleteness

Kids with Down syndrome.

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Prevention

Folic acid might have some impact on

preventing Down syndrome

The occurrence of Down syndrome is due to a random event that occurs during

formation of the reproductive cells, the egg, the sperm or the embryo. The age of the

mother is the only factor that has been shown to increase the risk of having a baby with

Down syndrome. This risk increases with every year, especially after the mother is 35

years old. By the age of 35, the risk for a woman having a baby with Down syndrome is

about 1 in 400 whereas the risk is 1 in 2000 for a mother of 20 years of age. The risk

increases to 1 in 35 when the mother is 45 years old. When the mother already has a

baby with Down syndrome, there is a 1% chance of having another baby with Down

syndrome. Also, when one of the parents is a balance carrier of translocation, the risk of

having a baby with Down syndrome is greatly increased. A balance carrier has some

rearranged genetic material but no extra genetic material, hence has no signs or

symptoms of Down syndrome 7,8.

There is no known way to prevent Down syndrome. However, a study in 1999 indicated

that impairments in folate/homocysteine metabolism could increase the risk of having

an infant with Down syndrome, suggesting a potential link between folic acid and Down

syndrome 9. Folic acid is essentially a water-soluble vitamin B that contributes to cell

division and growth; therefore it is particularly important for women during their

pregnancy. The Centers for Disease Control and Prevention (CDC) and other

organizations recommend that all women of child bearing age take 400 micrograms of

folic acid 1-3 months prior to pregnancy and keep taking it throughout the pregnancy 10.

Dietary folate and folic acid can ensure the health of moth-er and child 10.

Screening

Screening for Down syndrome is offered as a routine prenatal care. In fact, the American Congress of Obstetricians

and Gynecologists recommends offering various screening tests for Down syndrome to all pregnant women,

regardless of age. Some of those tests are carried out in the first trimester and some in the second trimester.

First trimester screening includes a blood test and a special ultrasound scan called nuchal translucency (NT) test. The

blood test measures the levels of two proteins in the maternal serum: free Beta-hCG and PAPP-A. This test is done

between 9 weeks and 13 weeks. The NT test measures the translucent (clear) space in the tissue at the back of the

baby. The NT test can only be done between 11 and 13 weeks. The accuracy of the first trimester screening range

from 79% to 90% 11. The first trimester screening provides information about the risk for the chromosomal

abnormities of the baby in the early stage of pregnancy.

Second trimester screening involves a blood test measures the levels of four substances in the maternal serum: AFP,

hCG, uE3 and inhibin A. This test could detect about 80% of babies with Down syndrome 11.

The combination of the first and second trimester screening is called integrated screening or sequential screening.

The integrated screening can detect 94-96% of babies with Down syndrome; therefore it is the most accurate

noninvasive screening test currently available 12.

Facts about Down syndrome 1995-2007*

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Diagnostic Tests

Although screening tests offer some certainty about the risk of having a baby with Down syndrome, they

are not confirmative tests and have a high rate of false positive and false negative.

The diagnostic tests include amniocentesis, chorionic villus sampling (CVS), and percutaneous umbilical blood

sampling (PUBS), which could identify babies with more than 99% accuracy 12. Unlike the screening tests, the

diagnostic tests are invasive and pose some risk of miscarriage.

Amniocentesis is a test that a sample of amniotic fluid surrounding the baby is withdrawn though a needle inserted into

the uterus. This sample is used to analyze the chromosome of the baby. This test is usually done in the fifteenth week of

pregnancy and carries a 1 in 200 risk of miscarriage.

Chorionic villus sampling (CVS) is a test that takes the cell sample from the mother’s placenta and uses the sample to

analyze the baby’s chromosome. This test is typically performed between ninth and fourteenth week of pregnancy and

carries a 1 in 100 risk of miscarriage.

Percutaneous umbilical blood sampling (PUBS) is a blood test in which the blood is taken from a vein in the umbilical

cord and tested for chromosomal abnormities. This test is usually done at the eighteenth week of pregnancy and carries

higher risk of miscarriage than amniocentesis and CVS. It is only performed when the result from other tests are not

clear.

Coping and Support

There are no cures for Down syndrome. Hence the treatment for the condition focus on

controlling symptoms and any medical conditions that result from Down syndrome.

Moreover, counseling and support that also recognized as important interventions in

treating individuals affected with Down syndrome. Although treatments and therapies are

for the physical, medical and cognitive problems associated with Down syndrome, the

following resources are starting places for parents and families of children affected with

Down syndrome:

Sharing Down syndrome Arizona (http://sharingds.org/)-a 501(C) (3) organization that tries to integrate all

individuals who are affected by Down syndrome by advocating positive acceptance and inclusion.

National Association for Down syndrome (http://www.nads.org)- gives educational resources and counseling

and support for parents of infants newly-diagnosed with Down syndrome.

Down Syndrome Network Arizona (http://dsnetworkaz.org/)- an organization that tries to educate, support and

advocate for those in our community impacted by Down syndrome.

National Down Syndrome Society (http://www.ndss.org)- offers research news and searchable resource

database and message boards to advance research on Down syndrome.

Parent to Parent link (http://www.parenttoparent.org)- a network of parents of children with special needs can

be matched for support and sharing experiences.

The Down Syndrome Research Foundation (http://dsrf.org/index.cfm?fuseaction=publications.dsq)- a

foundation dedicated to the advancement of research on ways of increasing the cognitive and social development

skills of children affected by Down syndrome.

Facts about Down syndrome 1995-2007*

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Arizona Birth Defects Monitoring Program

ABDMP Goals

The Arizona Birth Defects Monitoring Program (ABDMP) is a statewide, population-based, active surveillance pro-gram that collects and analyzes information on children with reportable birth defects diagnosed within the first year of life.

The goals of the ABDMP include :

To reduce the incidence of birth defects in Arizona from preventable causes.

To produce accurate statistics regarding the occurrence of birth defects in Arizona.

To identify, report, and investigate various birth defects trends, high-risk populations, and high risk locations.

To provide a resource for information about the incidence and epidemiology of birth defects for researchers, health professionals, hospitals, local health agencies, and others with a valid scientific or public health interest.3

150 N. 18th Ave, Suite 550 Phoenix, AZ 85007-3248

Phone: 602-364-1302 Fax: 602-542-7447

E-mail: shuo.yuan@azdhs.gov

We are on the web!

http://www.azdhs.gov/phs/phstats/bdr/index.htm

Facts about Down syndrome 1995-2007*

Medical Home Portal: http://www.medicalhomeportal.org/diagnoses-and-conditions/down-

syndrome/description - offers more information about Down syndrome.

With appropriate intervention, some patients with Down syndrome can live normally: go to main-

stream school, read and write, and have jobs.

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References

Arizona Birth Defect Monitoring Program

1. CDC. Birth defects: Facts about Down syndrome. Retrieved January 2012, from http://

www.cdc.gov/ncbddd/birthdefects/DownSyndrome.html

2. Wikipedia. Down sydrome. Retrieved January 2012, from http://en.wikipedia.org/wiki/

Down_syndrome

3. Mayoclinic. Down syndrome. Retrieved February 2012, from http://www.mayoclinic.com/

health/down-syndrome/DS00182/DSECTION=symptoms

4. Arizona Department of Health Services. 1998-2000 Arizona birth defects monitoring program

report. Retrieved January 31th, 2012, from http://www.azdhs.gov/phs/phstats/bdr/

reports/2007-06-15--1998-2000ABDMPReport-ForPrint.pdf

5. Parker SE, Mai CT, Canfield MA, et al. Updated national birth prevalence estimates for

selected birth defects in the United States, 2004-2006. Birth Defects Res A. 2010; 88: 1008-1016.

6. Besser LM, Shin M, Kucik JE, & Correa A. Prevalence of Down syndrome among children and adolescents in metropolitan Atlanta. Birth Defects Res A. 2007; 79: 765-74.

7. Mayoclinic. Down syndrome. Retrieved February 2012, from http://www.mayoclinic.com/

health/down-syndrome/DS00182/DSECTION=causes

8. Mayoclinic. Down syndrome. Retrieved February 2012, from http://www.mayoclinic.com/

health/down-syndrome/DS00182/DSECTION=risk-factors

9. Rosenblatt, DS. Folate and homocysteine metabolism and gene polymorphisms in the etiology

of Down syndrome. Am J Clin Nutr. 1999 Oct;70(4):495-501.

10. CDC. Folic acid. Retrieved February 2012, from http://www.cdc.gov/ncbddd/folicacid/

index.html

11. Babycenter. Tests during pregnancy. Screening for Down syndrome. Retrieved at February

2012 from http://www.babycenter.com/0_screening-for-down-syndrome_1519375.bc?page=3

12. Mayoclinic. Down syndrome. Retrieved February 2012, from http://www.mayoclinic.com/

health/down-syndrome/DS00182/DSECTION=tests-and-diagnosis

13. Down syndrome—Trisomy 21 or Mongolism. Retrieved at February 2012 from http://

www.doctortipster.com/3349-down-syndrome-mongolism-or-trisomy-21.html